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RE: Comment on "Meaning and the Semantic Web"

From: John Black <JohnBlack@deltek.com>
Date: Tue, 1 Jun 2004 21:12:59 -0400
Message-ID: <D3C8F903E7CC024C9DA6D900A60725D9057C2672@DLTKVMX1.ads.deltek.com>
To: "Dan Brickley" <danbri@w3.org>
Cc: <public-sw-meaning@w3.org>



> -----Original Message-----
> From: Dan Brickley [mailto:danbri@w3.org]
> Sent: Wednesday, May 05, 2004 4:10 AM
> To: John Black
> Cc: public-sw-meaning@w3.org
> Subject: Re: Comment on "Meaning and the Semantic Web"
> 
> 
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> John Black wrote:
> 
> |Bijan, Peter,
> |
> |In your poster paper, "Meaning and the Semantic Web",
> | 
> http://www-db.research.bell-labs.com/user/pfps/publications/me
> aning.pdf,
> | you make the following statement:
> |
> |"One might think that our account of meaning thus results in complete
> |anarchy in the Semantic Web. Even if so, we believe we have
> |embraced only those portions of anarchy that are necessary to prevent
> |totalitarianism, for any proposal for Semantic Web meaning
> |that cuts off easy access to disagreements will inevitably end up
> |stultifying the Semantic Web."
> |
> |I am finding this reference to totalitarianism hard to accept.
> |
> |In the first place, if you mean it literally, and a typical 
> definition
> |of totalitarianism reads like this, "Of, relating to, being, 
> or imposing
> |a form of government in which the political authority 
> exercises absolute
> |and centralized control over all aspects of life, the individual is
> |subordinated to the state, and opposing political and cultural
> |expression is suppressed: "A totalitarian regime crushes all 
> autonomous
> |institutions in its drive to seize the human soul" (Arthur M.
> |Schlesinger, Jr.)."
> |http://dictionary.reference.com/search?q=totalitarianism
> |Please explain how any of the proposals that have been discussed
> |could lead to this?
> |
> |In the second place, hoping that you mean this loosely and
> |metaphorically, even given one of the many proposals for fixing
> |the meaning of URIs, assuming they could work, what would prevent
> |you from creating an entirely new set of URIs with which to use to
> |make whatever contrary statements you desired?  Why is it *necessary*
> |for you to use anyone else's URIs at all?  If you are free to
> |create any URIs you may possibly need, with whatever meaning you may
> |wish to associate with them, in order to state whatever it 
> is you want
> |to state, how can you then say that another set of URIs forms a
> |totalitarianism?  For I have never seen any proposal that requires
> |that there be only one URI for any referent, but only proposals that
> |any URI have only one referent.  So there can be many URIs for any
> |referent.  So if you want to dissent, you can always create 
> a new URI.
> |
> |The model theory seems to allow for this:
> |"There are several aspects of meaning in RDF which are 
> ignored by this
> |semantics; in particular, it treats URI references as simple names,
> |ignoring aspects of meaning encoded in particular URI forms [RFC
> 2396]..."
> |http://www.w3.org/TR/rdf-mt/  Thus you can create any 
> *possible web* you
> |want, in order to say anything you want, and this would be 
> true even if
> |all *actual web* URIs were somehow given fixed meanings, wouldn't it?
> |This hardly seems a prescription for totalitarianism.
> 
> I took it as an allusion to the discussion of language/thought
> manipulation in Orwell's 1984. It is true that with SW tech anyone can
> create and promote their own RFD/OWL vocabulary. However we should
> always be wary of the influence we put into the hands of namespace
> authors when certain vocabularies become widely used.
> 
> For example, I can, it is commonly supposed, change the OWL/RDFS/HTML
> at http://xmlns.com/foaf/0.1/ and alter the (ahem) meaning of
> thousands (millions, actually) of RDF/XML documents. By editing a few
> files and typing 'make site', I can make docs that weren't currently
> true of the world, true of the world; and vice-versa.

But this is true if you owl:import http://xmlns.com/foaf/0.1/ also, 
isn't it? So the imports-only proposal offers no defense against this.
The meaning of documents under this proposal is just as dependent on the 
stability of the ontological context it imports as other documents are 
dependent on the stability of the schemas whose namespaces they include.

> 
> Since I'm a reasonably responsible person, this is probably not a big
> deal. I promise to be good. But try explaining that to someone
> building an ecommerce system that depends upon  externally-managed RDF
> vocabularies.

Right.  And now that you have explained it, I will refrain from using FOAF 
for anything serious until I have a way to make sure my documents are 
interpreted using the exact version of the FOAF spec that existed when 
I wrote them using that namespace or when I imported it.  Personally, 
I predict that you *WILL* change it at some point in a way that changes 
the meaning of millions of statements. And this is the point Tim was trying 
to make, I believe, when he said "that use of a URI in RDF implies a 
commitment to its ontology." 
http://lists.w3.org/Archives/Public/www-tag/2003Jul/0022.html For, just as 
changing the FOAF spec. would alter the sense of millions of documents, 
failure to use the correct FOAF spec., when interpreting some RDF document 
dependent upon it, would alter the sense of the document.  If it is "good" 
of you to refrain from changing the spec. in this way, it seems it would 
be similarly good of you to use the spec., that is commit to it, when 
interpreting someone's URIs.  The scale is different but the effect is 
the same.  By refusing to respect the ontological context of a document, 
"I can make docs that weren't currently true of the world, true of the 
world; and vice-versa."

> 
> IMHO it is reasonable to expect that the actual usage of RDF terms be
> taken into account when accounting for their meaning in any broad
> social / real-world sense...
> 
> Dan
> 
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Received on Tuesday, 1 June 2004 21:13:00 GMT

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